This application claims the priority of German Application No. 199 30 691.5, filed Jul. 5, 1999, the disclosure of which is expressly incorporated by reference herein.
The invention relates to a dispensing device for liquid dishwasher detergent in dishwashers.
Dispensing devices in which an intermediate chamber or dispensing chamber is sequenced to follow a supply chamber for wetting agents are already known in dishwashers. In these, a double-valve plunger actuates in an opposing manner the valve function in the opening between supply chamber and dispensing chamber as well as that of the discharge opening of the dispensing chamber to the wash area of the dishwasher. This means that given a single application of current to the actuating solenoid valve, the opening between the supply chamber and dispensing chamber is opened and the outlet opening of the dispensing chamber is closed. During the transition to the de-energized state, the dispensing chamber is closed vis-xc3xa1-vis the supply chamber, and the outlet opening is opened so that the wetting agent flows into the wash area. This arrangement with two chambers serves to specify, based on the specified volume of the dispensing chamber, a fixed dispensing volume such that with each application of current to the solenoid, wetting agent is also fed into the wash area of the dishwasher.
These dispensing devices are usually combined with a chamber to accommodate the detergent. This chamber is opened to feed the detergent into the wash cycle by a hinged door which is locked in its closed position and opened by spring pressure after an unlocking procedure. For reasons of cost, the unlocking procedure is effected by the same solenoid used to dispense the wetting agent. In order to maintain the program sequence of the wash process, specifically in terms of the feed of the appropriate detergent or wetting agent, it is necessary that only the hinged door of the detergent chamber be actuated during the initial application of current to the solenoid, and the dispensing of wetting agent be actuated only upon the subsequent application of current to the solenoid. In commercially available dishwashers, a lever arrangement with a ratcheting device is employed for this purpose. The ratcheting device causes the actuation lever for the wetting agent to click into place during the initial application of current, and the valve to actuate for the wetting agent only after the second application of current. When the dishwasher door is opened, the ratchet mechanism is returned to the starting position by gravity so that a wash program can start its sequence again from the beginning.
In contrast to the above, the object of the invention is to propose a dispensing device in which a detergent valve for dispensing wetting agent may be rigidly coupled to the actuating member while still allowing the wetting agent to enter the wash area only after a second actuation of the actuating member.
This object is achieved according to the invention with a dispensing device for dispensing liquid detergent in a wash area of a dishwasher in which a supply chamber for the detergent and a detergent valve are provided. The device is pivotable between a fill position and an operating position and is characterized in that provision is made for: in the direction of flow to the wash area behind the detergent valve, a dam to retain the detergent in the operating position and a return channel to return at least a portion of the retained detergent to the fill position.
Advantageous embodiments and further developments of the invention are described herein.
Accordingly, a dispensing device according to the invention is characterized in that provision is made for a dam behind the detergent valve in the direction of flow to the wash area, which dam is to retain the detergent in the operating position, and for a return channel for the return flow of at least a portion of the retained detergent in the fill position.
In this arrangement according to the invention, the retained volume in front of the dam is filled with detergent during the initial actuation of the actuating member, while a second function, e.g., unlocking a hinged door of a detergent chamber may be effected by the actuation member. The wetting agent retained by the dam cannot reach the interior of the wash area during this process. The dam may, as explained below, be designed in various ways such that wetting agent is able to override the barrier and reach the interior of the dishwasher only after the second actuation of the actuating member.
In order to reset the initial position of the dispensing device, it is necessary that the retained wetting agent be at least partially removed from the area in front of the dam when the dishwasher door is opened, for which purpose the return flow channel is provided. After the dispensing device has pivoted into the operating position, which action is usually effected when the dishwasher door is closed, the retained volume in front of the dam is again available for filling in response to the initial actuation of the actuating member.
In this type of dispensing device, the detergent valve may be rigidly joined to the actuating member, for example, to the armature of a solenoid.
The simultaneous actuation of the detergent valve along with an additional function, e.g., the opening of the hinged door of the detergent chamber, is permissible in the dispensing device according to the inventionxe2x80x94with the result, for example, that the aforementioned lever arrangement may be dispensed with, or that the valve body of the dispensing valve may be designed to function simultaneously as the armature of the solenoid.
The dispensing device according to the invention may be employed in connection with any desired design for the actuating member and is not limited to the use of a preferred specific solenoid.
Additionally, the invention is of benefit not only in combination with a separate detergent chamber but also for any conceivable utilization in which the appropriate detergent is intended to be fed to the wash area of the dishwasher only after the second actuation of the detergent valve.
In one particular embodiment of the invention, the dam for the detergent is designed as an overflow. Here the actuation of the actuating member, for example, of a solenoid, must occur within the time period in which the level of the detergent does not exceed the height of the dam. With the next actuation of the detergent valve, the detergent is then able to override the overflow and reach the interior of the dishwasher.
In a preferred further development of the invention, the dam includes a discharge opening closable by discharge valve. Such a double valve arrangement is advantageous from the point of view of a failsafe design since it ensures that even if the first detergent valve is defective, no wetting agent can reach the area of the diaphragm which seals the detergent valve from the outside and which is usually present in previous dispensing devices.
The discharge valve may be actuated as a simple safety valve co-directionally to the detergent valve, which means that both valves open simultaneously and close simultaneously.
In one particular embodiment, however, the outlet valve may be coupled mechanically in opposition to the dispensing valve. This means that when the dispensing valve closing off the supply chamber opens, the discharge valve is closed and, conversely, when the dispensing valve is closed, the discharge valve opens.
This embodiment offers an advantageous combination of a dispensing chamber which encompasses the dam according to the invention. Upon the initial actuation of the actuating member, the discharge opening of the dispensing chamber is closed, while the detergent valve and thus the feed from the supply chamber is opened. In this position, detergent flows out of the supply chamber into the dispensing chamber.
Here, the dam is defined by the position of the discharge opening in the dispensing chamber. Said chamber must be designed sufficiently high that even after the actuating member is switched off, during which off-period the feed from the supply chamber is closed while the discharge opening of the dispensing chamber is open, no detergent reaches the area of the discharge opening but is instead retained in front of it at the wall of the dispensing chamber.
In response to the next actuation of the actuating member, the dispensing chamber may then be completely filled with the discharge opening closed. When the actuating member is subsequently switched off, the inlet from the supply chamber is again closed and the discharge opening opened once again. The detergent may now flow out into the wash area until the level in the interior of the dispensing chamber lies below the discharge opening. This dispensing process may be repeated as many times as needed, the available dispensing volume being the residual volume of the dispensing chamber immediately below the discharge opening. This dispensing volume corresponds to the total volume of the dispensing chamber minus the retained volume.
After the wash process is completed, the dishwasher is opened while the dispensing device pivots into position. In the process, at least a portion of the detergent in the dispensing chamber flows out through the return opening such that when the machine is operated once again, the volume retained in the dispensing chamber is at least partially available, and detergent may, according to the invention, only reach the wash area in response to the second actuation of the actuating member when the required actuation of the actuating member occurs.
In another embodiment, two additional chambers, i.e., an intermediate chamber and an outlet chamber, are sequenced to follow the supply chamber. Said outlet chamber here encompasses the dam according to the invention for the detergent. The additional chamber allows the intermediate chamber to be filled above the level of the closed discharge opening when the actuating member is first actuated. After the actuating member is switched off, the connection between the supply chamber and the intermediate chamber is interrupted, whereas the connection from the intermediate chamber to the outlet chamber is opened.
As a result, detergent then flows into the outlet chamber where it accumulates in front of the dam provided there.
The outlet chamber may in turn be provided with a discharge valve at the outlet, which valve is rigidly coupled to one or both of the aforementioned valves, the valve between the supply chamber and the intermediate chamber, as well as the intermediate valve between the intermediate chamber and the outlet chamber. The coupling may be implemented in such a way that the valves between the supply chamber and the intermediate chamber are opened and closed simultaneously with the discharge valve of the outlet chamber, while the valve between the intermediate chamber and the outlet chamber moves in the opposite direction. The entire arrangement may be designed as a system of communicating tubes.
When the actuating member is actuated, detergent flows from the supply chamber into the intermediate chamber, which is closed on the outlet side. After actuation is switched off, the detergent flows from the intermediate chamber, into the outlet chamber which is closed when a discharge valve is present or otherwise is provided with an overflow barrier.
When the actuating member is actuated again, the detergent is fed through in the same wayxe2x80x94in the case of a discharge valve, the detergent in the outlet chamber can flow out during actuation of the actuating member; or in the case of an overflow barrier in the outlet chamber, the overflow overflows as soon as detergent flows through into the intermediate chamber after the actuating member switches off.
Said chambers need not necessarily be arranged next to one another in order to obtain an equalization of the detergent levels in them, but may be situated at different levels. In particular, it is possible, when the outlet chamber is used, to locate this chamber completely below the intermediate chamber so that the outlet chamber may be filled completely and used as a dispensing chamber.
Since in the case of an outlet chamber with a dam, the outlet chamber must also be reset to the start position when the dishwasher is opened, the outlet chamber is provided with a return opening so that the outlet chamber can empty at least partially when the dishwasher is opened.
The return flow of detergent when the dishwasher door is opened may, for example, proceed directly into the supply chamber for the detergent in each of the embodiments discussed.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.